Nothing, because UBI+salary = previous salary. So everyone's part of income available for paying rent is the same.
Only difference is that the guy who earns $2500 right now might be able to get a better job because he can quit without immediately losing his apartment.
I can't see inflation not catching up with whatever UBI provides within couple of years. In the example above, rent will go obviously up, as will prices of products and services. When everybody has more money, I for sure can ask for more for my services/products.
As for dependency, the money won't magically spawn on the table, they will be earned by state on taxes and then paid to citizens/residents. So you depend on who is in power anyway since there will be many rules, exceptions etc. It brings another new universe for corruption, leftist politicians to promise (and deliver) higher payments that next generations will have to pay back and so on...
All these mental games, me, you, everybody... we can't get the full picture of everything mixing up with everything else - economy, mentality of individual and groups, greediness, black swan events, selfishness etc. and come up with a nice simulation how it will end up all joined together. That's just wishful thinking and people pick up side which they prefer, nothing more.
Only difference is that the guy who earns $2500 right now might be able to get a better job because he can quit without immediately losing his apartment.